Retaining rings



Nov. 25, 1958 H. WURZEL RETAINING RINGS 2 Sheets-Sheet 1 FIG.4

Filed Feb 7, 1956 FIG. 3

FIG.5

Bore Dia iNVENTOFt HUGO WURZEL ATTORNEY Nov. 25, 1958 Filed Feb. 7, 1956H. WURZEL 2,861,824

RETAINING RINGS 2 Sheets-Sheet 2 FIG. I FIG. 2

ia/4 4 k FIG. 7 FIG. 8

1 l5 I \K l /s 1r INVENTOR HUGO WURZEL ATTORNEY United States PatentRETAINING RINGS Hugo Wurzel, Bronx, N. Y., assignor to Waldes Kohinoor,Inc., Long Island City, N. Y., a corporation of New York ApplicationFebruary 7, 1956, Serial No. 563,912

1 Claim. (Cl. 287-52) This invention relates to improvements inretaining rings of the type adapted to form an artificial locatingshoulder on a shaft or in the bore of a housing, and more particularlyto an improved internal retaining ring and an assembly incorporatingsuch a ring.

It is well known from the Heiermann Reissue Patent No. 18,144, datedAugust 4, 1931, and later patents issued to the assignee of the presentapplication to construct elastically deformable internal retaining ringsas a split or open-ended spring-ring body having section height (radialwidth) which decreases progressively from the middle section to the freeends and with a width of gap between said free ends enabling said ringsto be compressed to an outside diameter less than the bore of thehousing in which the ring is to be assembled, Whereby the ring may beinserted in the bore to the axial position of the groove in which thering spring-seats itself when released. In the design of such anelastically deformable ring the width of the gap as well as the maximalsection height of the ring (which latter as explained in patent toHeimann No. 2,574,034, dated November 6, 1951, and corresponding BritishPatent No. 685,982, dated January 14, 1953, is derived from the formulalp E h and the depth of the groove in which the ring is to be releasedhave to be so dimensioned that the maximal permissible working stress towhich the ring is exposed is not exceeded. At the same time it is highlydesirable that this working stress be chosen as high as possible, thatis to say, up to the yield strength of the material of the ring, therebyto provide the greatest possible height in the ring shoulder, on the onehand, and in the depth of the groove, on the other.

The aforesaid allowable working stress of such a ring depends on thecharacteristics of the ring material, especially on its hardness which,in turn, depends on the heat treatment to which it is subjected in beingrendered springy. As the heat treatment cannot be maintained absolutelyconstant, it frequently happens that the ring, even though the width ofits gap has been calculated correctly with respect to section height,ring diameter and yield strength of the material, takes on a permanentset when compressed for the first time, after which, on being released,it does not regain its original gap width and original free diameter.Any loss in free'ring diameter is of course highly objectionable becauseit decreases the pressure grip of the ring against the bottom of itsgroove, and hence the ring possesses less than its theoretical security.Furthermore, it may happen that a ring which has suffered a loss in freediameter as aforesaid, upon being released into the deepest groove for vwhich it is designed, i. e. a groove having the proper calculated depthplus the maximum necessary tolerance,

no longer abuts the groove bottom but, instead, seats such anundesirable condition is the more frequent the more sensitive the ringmaterial is to heat treatment.

Stated broadly, a main object of the invention is to eliminate thepossibility of ring insecurity as results from an internal ring havingtaken on an unwanted permanent set as aforesaid, both in thering-to-groove bottom at tachment, and also in the ring assembly as awhole.

A more particular object of the invention is the provision of aninternal retaining ring characterized, prior to its initial compressioninto a housing bore, for example, by a free diameter (and acorresponding width of gap) which is larger than the free ring; diameterand gap width of a standard elastically deformablering ascertained bycalculation to be the correct diameter and gap Width for the particularintended ring application, by an amount such that, consequent to itsinitial compressing, the ring will take on a predetermined permanentset, but only to the degree that the ring does not become smaller interms of free diameter and width gap than the calculated or standardring.

Another object of the invention is the provision of an internalretaining ring characterized as aforesaid and which yields the furtheradvantage that the depth of the seating groove for said ring may beincreased to a certain amount as results from the fact that the groovediameter may be enlarged up to the diameter of the ring after it hastaken on a permanent set. This is a particular feature of advantage withsmall rings of .75" down to about .25", because such small rings areparticularly prone to being permanently set so that, previously, groovedepth and thrust load had to be kept within rather small limits.

Yet another object of the invention is the provision of a retaining ringinitially having an enlarged free diameter and gap width as compared toa standard calculated ring, as aforesaid, and which is furthercharacterized in that its groove-seating (outer) edge is beveledaccording to United States patent to Bluth No. 2,509,081, dated May 23,1950, which with the present application is commonly owned. As isdisclosed in said patent, such beveled rings engage their groove more orless deeply, according to the play between the ring and machine part tobe located by the shoulder formed thereby, with the maximum play whichsuch beveled rings may take depending on their free diameter which,according to the present invention, reaches the full calculated optimumonly after the first compression thereof.

The above and other objects and features of advantage of an internalretaining ring according to the present invention will appear from thefollowing detailed description, in which reference is had to theaccompanying drawings, in which- Fig. 1 is a stress diagram graphicallyillustrating the conventional (standard or computed) ring dimensioning;

Fig. 2 is a similar view illustrating ring dimensioning according to theinvention;

Fig. 3 is a plan view of a ring according to the invention havingenlarged free diameter and gap width as compared to the conventionalring, i. e. a ring of the invention prior to being permanently set byits first compression;

Fig. 4 shows the ring of Fig. 3 after having been compressed andreleased for the first time, as results in the ring taking on apredetermined permanent set;

Fig. 5 shows the same ring compressed before entering the bore of ahousing;

Fig. 6 is a comparative view illustrating a ring with conventionaldimensions shown in full lines, and a ring with dimensions according tothe invention. in dottedlines, the latter after the first set;

Fig. 7 is a section through a ring assembly comprising a housing havinga bore, a groove in the housing bore,

-of a conventional internal retaining ring dimensioned according tostandard calculations which graphically illustrates the stressconditions in the ring plotted against the progressively closingpositions of the gap as abscissae, and numeral 2 designates the maximaltension s in the middle section of the ring when-the gap is completelyclosed, it being assumed that the yield strength of the material ofthering has been exceededto a certain degree consequent to full closingofthe gap. Upon release of .the ring to its groove, the gap of courseopens up again,

but not to its original width a, but, rather, to a lesser "value b. Thatis to say, the ring has taken on a permanent set ab in its firstassembly.

Fig. 2 graphically depicts the stress conditions existing in a ringaccording to the invention, again against the progressively closingpositions of the gap as abscissae. The original gap has a width agreater than gap-width -a as aforesaid, and it will be noted also thatthe tension -s' (designated at 2') in the ring middle section is, ac-

cording to the stress curve 1', greater than s aforesaid :when thegap iscompletely closed. When released, the

n'ng opens up again, but only to the lesser .value b, so

that, here again, a permanent set a-b takes place. However, since thestress s is substantially greater than "the stress s, the new gap widthb is also larger than. b

aforesaid. More particularly, according to Fig. .2, said new gap widthis approximately equal to the original gap a of the conventional(standard) ring illustrated in Fig. 1.

The course and slope of the stress curve 1' (Fig. 2) also shows that byincreasing the original gap of conventional internal retaining rings byapproximately 30-50%, and the free diameter of said rings to about 1112%of their bore diameter as compared with 9-10% :for the conventionalrings, there is achieved the desir- ..able effect that, after .the firstset of the herein proposed internal spring retaining rings .as resultswhen their ring .endsare brought together, the final or residual gap issubstantially equal to the original gap of conventional 4 rings.

It is to be observed, however, that the gap width may not be increasedtoan excessive degree becausea one-sided distortion may then occur dueto the possibility that the ring arms are not perfectly symmetrical.

Translating the above. theoretical considerations into ring structure,reference numeral 10 (Fig. 3) illustrates .apertured cars 11, 12,substantially as shown.

an internal retaining ring according to theinvention which, as usual,comprises an open-ended ring body whose inner and outer edges arepreferably eccentric, with the eccentricity being :in direction suchthat the ring 'body has progressively decreasing section height (radial.width) from its middle section to its free ends, which latter may beformed as radially-inwardly protruding According to the invention such aring body has a wider gap between its open ends than the gap with whichconventional internal retaining rings of corresponding size areprovided. That is to say, a ring of the invention is shown -to' have agapwidth of 46 (approximately 12.8% of the ring circumference) prior ,toits being initially com pressed in first assembly thereof as against 36(or 10% of the ring circumference) with the conventional internalretaining ring as previously designed. .However, as

1 seen in .Fig. 4, when the present ring is compressedas by bringing itsends together as in Fig. 5,,thus to reduce ..--.external ring diameterto slightly less than the diameter of the housing bore in which the ringmust be inserted :,:and shifted along inassembly, the ring takes on a,per-

-,;ma11e nt set which. decreases the. gap but,not to, below 2% for thestated gap width.

36. Thus, the ring upon being sprung into its groove (provided, ofcourse, that the depth of the groove is such as to permit the ring torelease to its free diameter) has gap width corresponding to the gapwidth of the conventional ring before it has taken on its permanent setconsequent to being first assembled in its groove.

Referring to Fig. 6, such compares in one view a ring according to theinvention, after it has taken on its predetermined permanent set, with aknown retaining ring before the latter has acquired a set consequent tofirst compression thereof in assembly. As canreadily be seen the ring 10as herein proposed (shown in dotted lines) has, after setting, asomewhat wider gap than that of the conventional ring 10a prior to itshaving been permanently set, and similarly the free diameter D of theherein ring, after it has taken on a permanent set, is also slightlygreater than the free diameter D of the conventional ring before it hasbeen set. by its, first compression.

The functional differences present between the herein proposed andconventional rings in their respectiveassemblies will also be clearupon. analysis of Figs. 7 and 8, in which reference numeral 10a (Fig. 7)indicates a conventional ring seated in a groove 15 provided therefor inthe bore 16 of a housing 17. If the ring 10a is to have pressure grip onthe bottom of the groove 15, it

indicated) or, at best, having but non-pressure sliding contact with,the bottom of the groove 15.

But if the outside diameter of a ring upon the latter being compressedin the bore 16 and releasedto the groove v15 is caused to remain aslarge as the outside free diameter of the conventional ring 10a beforebeing assembled in said groove, the ring will pressure-grip itselfagainst the bottom of a groove having full calculated depth. Such isintended to be illustrated in Fig. 8, wherein a ring 10 corresponding tothe Fig. 4 ring is full-seated in the groove 15. That is to say, thering initially had diameter and gap width larger than calculated for theyield strength. of the ring material and/or the depth of the groove 15but it has taken on a permanent set in amount as effects reduction insaid gap width and a corresponding reduction in said ring diameter tovalues resulting in the ring 10 seating in the full-depth groove 15 ascalculated for the particular assembly. This means that the ring 10 hasgreater security than the ring 100. and also that it makes full use ofthe optimum calculated groove depth in resisting thrust loads.

"The following numerical comparisons between the conventional and thepresent improved internal retaining rings are also offered as an aid infurther disclosing the invention. Whereas the conventional ring withprogressively decreasing section height has a gap width of approximately56 (10% of the ring circle) and a section height calculated according tothe yield strength for the particular section height, the improved ringof the invention has, for the same section height, a gap width ofapproximately 45-55 (or approximately 12-15% of the ring circle), sothat in fully closing the ring the yield strength at the middle sectionof the ring is considerably exceeded. The free outer diameter of theimproved ring according to the invention is correspondingly larger thanthe free diameter of the conventional ring, i. e. by about That is tosay, that whereas the original (free) diameter of the conventional ringexceeded the diameter of the housing bore by 9- l0%,

thus being approximately 1.1 of housing borediameten the original (free)diameter of the improvedring exceeds ,the

housing bore diameter by 11-13%, or approximately 1.12+ of said housingbore diameter.

Preferably, the outer or groove-seating edge of the ring is beveled asat 20 in the manner disclosed in the commonly owned Bluth et a1. PatentNo. 2,509,081. As explained above, beveled rings according to saidpatent seat in their grooves more or less deeply in accordance with theplay between the ring and the machine part being located by the ring,with the maximum play which the beveled ring may take up depending onits free diameter. Since according to the invention the free di ameterof the ring reaches its full calculated optimum upon the ring beingfirst set, beveling of its grooveseating edge according to said Bluth eta1 patent enables said ring to take up a greater amount of end play thanthe conventional ring whose free diameter is reduced from its calculatedoptimum consequent to the first setting thereof.

Without further analysis, it will be appreciated that the improvedinternal retaining ring and assembly utilizing same as herein disclosedachieves the desirable objectives therefor outlined in the foregoing.However, as many changes could be made in carrying out the aboveconstructions without departing from the scope of the invention, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

I claim:

An internal spring retaining ring adapted for assembly in a grooveprovided therefor in a housing bore and thereupon to form an artificialshoulder for axially locating a machine part in said bore comprising anopen-ended ring body of spring material having a gap between its openends enabling said ring body to be compressed in assembly, the sectionheights of the ring body decreasing progressively from its middlesection to substantially its free end whereby the ring maintainscircularity when compressed, the outer free diameter of said ring beingapproximately 1.12+ of the housing bore diameter and the width of saidgap being approximately 12-15% of the outer circumference of the ringbody, said ring body contracting to an outer diameter slightly less thanthe bore diameter when its free ends are brought substantially togetherand upon release following its first such contraction, expanding to anouter diameter which is less than its initial free diameter butsubstantially equal to the diameter of the circle of the groove bottom,the construction and arrangement being such that in said contraction thering body takes on a slight permanent set by an amount such that itsfree diameter after release is not smaller than the initial freediameter of an elastically deformable ring having the same sectionheights and adapted for assembly in the same housing bore.

References Cited in the file of this patent UNITED STATES PATENTS2,509,081 Bluth et a1. May 23, 1950 2,560,917 Bebinger July 17, 1951FOREIGN PATENTS 685,982 Great Britain Jan. 14, 1953

